Highly read on www.bmj.com in August

Three large, long-running health surveys suggest that some fruits — but not fruit juice — reduce the risk of diabetes.

Researchers led by Qi Sun at the Harvard School of Public Health in Boston, Massachusetts, looked at people's reports of how often they ate certain fruits and whether they developed diabetes. Results came from a total of 187,382 US health professionals whose health and habits have been tracked for more than two decades, during which time more than 12,000 of the study participants developed diabetes.

Eating whole fruits such as apples, pears, grapes, raisins and particularly blueberries was associated with a lower risk of diabetes. By contrast, drinking fruit juice was associated with a slight increase in risk, perhaps because juices contain fewer fruit-specific chemicals and introduce more sugar into the bloodstream more quickly.

Br. Med. J. 347, f5001 (2013) http://dx.doi.org/10.1136/bmj.f5001